Eccentric president managed to divide Right (8)
I believe the answer is:
aberrant
'eccentric' is the definition.
(thesaurus)
'president managed to divide right' is the wordplay.
'president' becomes 'Abe' (Abraham (Abe) Lincoln).
'managed' becomes 'ran' (I've seen this before).
'to divide' means one lot of letters goes inside another (some letters create a division in others).
'right' becomes 'rt' (abbreviation as in Rt Hon- the Right Honourable).
'ran' inserted into 'rt' is 'rrant'.
'abe'+'rrant'='ABERRANT'
(Other definitions for aberrant that I've seen before include "rogue" , "untypical" , "Deviating from the norm, at barren state" , "Wandering, straying" , "Irregular" .)